The owner soon arrived with his son. According to the Pearl River Co. Sheriff's Dept., the spat escalated into a gun battle.

"During this argument, we believe there might have been some pushing and shoving," Chief Deputy Shane Tucker told the Sun Herald. "One of the customers and one of the owners produced firearms. We don’t know who shot first."

Both fathers and both sons were wounded.

The father and son customers were discovered dead in the store when authorities arrived.

The owner and his son were seriously injured and transported in a helicopter to a hospital. The son was upgraded to stable condition on Sunday.

Tucker said the investigation into the incidents could take weeks.

"It's still under investigation. There will be lots of work to sift through the evidence collected and statements and see where that steers the investigation," he said. "That will be done in the following weeks and months."